This invention relates generally to motor end shields, and, more particularly, to cast motor end shields including an insert and a method for casting the end shields.
Motors typically include a housing connecting two end shields, each end shield having an opening therethrough. The housing and end shields surround a stator core having a bore therethrough. A rotor, including a rotor core and a rotor shaft, extend through the stator bore. The rotor shaft extends through the end shield openings. A bearing, positioned at each end shield opening, contacts the rotor shaft and an inner diameter surface of each end shield. If the inner diameter surface is not properly sized, shaped, and oriented, excessive noise, vibration, and wear may result.
Typically, cast end shields (for example, fabricated from aluminum), include a steel insert ring for contacting the bearings. The insert ring is positioned by a mold utilized to cast the end shield. Typically the mold includes a protrusion on one half of a cope and drag casting pattern. The final location of the insert in the casting is a result of the inner diameter tolerance of the insert and the tolerance of the tapered protrusion. Thus, proper placement and orientation of the insert ring is difficult.
In an exemplary embodiment, a cast end shield includes an insert ring and three slots extending to the insert ring. The end shield also includes an opening extending therethrough and the insert ring is oriented at the opening such that an inner diameter of the insert ring is exposed by the opening. The insert ring is a substantially circular steel insert ring concentric with the opening.
A method of fabricating the end shield includes providing a mold comprising a center axis, a rotor projection coaxial with the axis, and a plurality of orienting projections extending from the rotor projection. The insert is oriented around the rotor projection such that the insert contacts the orienting projections. The end shield is cast such that the insert is embedded within the end shield and an inner diameter surface of the insert ring is exposed.